In a series of tweets advertising his companies this week, Musk said, "There are way easier places to work, but nobody ever changed the world on 40 hours a week."

Many on Twitter were quick to point out the errors in Musk's observation:

One woman was keen to mention the example of Alexander Fleming, the scientist who changed the world by going on vacation and accidentally leaving a petri dish open near a window, leading to the discovery of penicillin.

As so many on Twitter said, changing the world has little to do with the number of hours one works and everything to do with the impact and quality of that work. Countless people have made history without the requisite of working more than 40 hours every week.

Though studies have found that working more hours generally does lead to higher corporate positions, it is also correlated with anxiety, depression, and worse sleep.

But studies say that sleep deprivation is ultimately harmful— it's linked to certain cancers, chronic diseases like Alzheimer's, and heart disease, and it can do serious damage to your immune system in general.

Of course, every person's needs are different, and Musk's schedule may work for him. But the health risks of more work and less sleep are undeniable, and it's significantly more difficult to change the world if you're sick, or dead.